No problem, let's work through this together. We're starting with 8081 and 1900 and adding them all up.

Step 1: We'll start by adding the digits 1 & 0 in column 1 and get 1.

Step 2: We'll start by adding the digits 8 & 0 in column 2 and get 8.

Step 3: We'll start by adding the digits 0 & 9 in column 3 and get 9.

Step 4: We'll start by adding the digits 8 & 1 in column 4 and get 9.

So, 8081 + 1900 = 9981.

